Method of preparing facsimile transmission copies for degraded reception



July 22, 1952 M. MORRISON 2,604,532 METHOD OF PREPARING FACSIMILE TRANSMISSION COPIES FOR DEGRADED RECEPTION Filed Oct. 17, 1950 Fig.1

INVENTQR.

Patented July 22, 1952 METHOD OF PREPARING FACSIMILE TRAN S- MISSION COPIES FOR DEGRADED RE- OEPTION Montford Morrison, Rochester, N. Y. 7 Application October 17, 1950, Serial No. 190,565

The present invention relates generally to forms of alphabetic and mineral characters, more particularly to forms of such characters suited to telegraphic facsimile transmission, and specifically to forms of such characters when transmitted over circuits having degrading interference, and/or fading at the reception terminal.

The present application is a continuation in part of application Serial No. 677,662 filed July 19, 1946.

The invention is not limited to the English alphabet nor to the so-called Arabic numerals, but

for simplicity of disclosure that alphabet and those numerals will be treated exclusively.

One object of the invention is to delineate characters on a support for facsimile transmission in forms which permit of a greater amount of transmission character deformation without character confusion, than is practical with conventional forms of alphabets and numerals.

Another object of the invention is, on a facsimile transmission copy, to assign different dimensions to the character elements which may otherwise lead to confusion; that is, differentiation between characters by comparison of certain character elemental dimensions.

A further object is to restrict the delineating of characters on a facsimile copy to such forms as do not require a fundamental modulation frequency of more than 3 cyclesper character.

In the prior art, type forms which have been used in facsimile transmission have been designed to possess a motif of design characteristic which is calculated to make letters look related. For instance, vconsider typewriter characters-the C and G; the P, B and R; the O and Q; the E and F. Each of these groups have only one element different, and in each group one letter can be formed into the other by the addition or subtraction of a single stroke. The present invention seeks to reduce the possibility of such a change of character form by such a simple addition or subtraction. I

Further in the prior art, type forms which have been used in facsimile transmission have been designed with some of the strokes of some of the letters very close together relative to other letters, like N, M, W, A as compared to D, O, U, P. The former group requires a relatively much higher fundamental modulation frequency than the latter group. The present invention seeks to reduce the maximum fundamental modulation frequency of such letters as are illustrated in the first group above.

It is well known in the art of multiple channel voice-frequency carrier-telegraph circuits; that the transient effect, at the beginning and at the endv of. a marking signal in one channel, causes current flow in adjacent channels, of values higher than the flow in the same adjacent '7 Claims. (01. 178-5) channels due to steady state flow of current in the said one channel. This means that transmission of repeated dot signals in such a system, constitutes one source of inter-channel interference, which may in no small way be a troublesome source of character deformation. The present invention seeks to reduce this interchannel interference by employing strokes in the formation of characters on a facsimile copy in such a way that these transient effects occur, where ever possible, at signal time positions to cause a minimum of spill over in adjacent channels,. that is when adjacent channels are working anyway and therefore spill over adds nothing to the received copy.

The nature of the invention resides in a method of delineating characters on a support for optical pick-up in a facsimile transmitter, to accomplish a new and useful result in a facsimile receiver, rather than'does the invention relate to any ornamental character design, orto any particular specific design of characters.

Reference may be had to the drawing in which Fig. 1 shows one embodiment of the invention in an English alphabet, and in a set of Arabic numerals; Fig. 2 is a graph to the scale of Fig. 1 showing the maximum fundamental modulation frequency of 3 cycles per character, required to transmit any of the characters of Fig. 1.

In embodying the invention in delineating characters on a support, reference may be had to Fig. 1, which may be itself taken as a facsimile transmission copy. In practice the vertical and horizontal guide lines would be absent, since they are included on the patent application drawing merely for convenience and clearness of disclosure.

In considering Fig. 1, the characters will be thought of as a copy for transmission in a seven channel telegraphic printing system, such as described in U. S. Patent No. 2,425,950 to the applicant and the several channels will be referred to herein by the numerals I, '2, 3, 4, 5, 6 and 1, the numeration of the channels starting from the top and progressing down, that is, the top channel of the character being No. I and the bottom channel being No. I.

In conventional type such as used for typing messages, such as typewriter type for instance, one group of letters which are subject to confusion by deformation are C, D, G, O, Q, and U. With the loss or gain of practically a single stroke the C and G may be confused. Referring to Fig. 1, channel No. I of these two letters are formed differently; there is a difference in channel No. 2; channels 5, 6 and 1 have differences; so that instead of having to consider practically the existence or non-existence, of a single stroke, there are 5 checks or 5 channel recordings that can be used to determine the character. These are transverse checks; but also there will be observed that thelongitudinal dimensions of the characters provide further checks on differentiating the characters.

Similar differences will be found between the letters D, O, Q andU of Fig. 1.

Conventional forms of B,'P R, E, F, H and S are easily confused by deformation through racsimile transmission. Referring to Fig. 1 these letters not only have diflerencesin the forms which characterize them, but also the horizontal these letters are at definite different altitudes, which alone greatly reduces any likelihood of confusion. The horizontal stroke alone avoids any confusion between B, P and R, and between E and F.

I, -J and L, are difierentiated by channel: differerrces' and by the dimensional'time position of the vertical stroke. I and Tare difierentiated mainly by channel Nos. 1 and 2', but a base may be added to the T in channel Tl if found :advantageous.

M and N are not easily confused because of the bulk in channels '5, 6 :a'ndl, of N. Further these letters are so delineated that the space between any two 'marks .in any channel of these characters is never less than the period of ahalf cycle of 'a frequency of 3 cycles per character. See Fig. 2. I This lfact is also true of all the other letters and numerals of Fig. 1. g

This means that the maximum fundamental modulation frequency required for transmitting these characters is '3 cycles per character, which is of the order of modulation frequency of .a Baudot 'code printer, and not approached by any facsimile system employing conventional characters. V s

The method of delineating the remaining characters of Fig. l, is carried out by the same methods as set forth for the characters already described and fit is believed "that no useful value would be added to this specification by pointing out in minu'te detail the exact diiierencesin all the other characters; since, one skilled in the art will be able to m'a'k'e and use the invention as herein disclosed and modify the :forms' of the characters without departing :from the spirit of 'theiinvention. f

I claim: V

l. The method or" preparing a message copy composed of alphabetic characters for reduction oi character confusion by interference in reception in an electrical facsimile system employing optical copy scanning for signal pick-up for transmission which comprises, printing on a suitable support letters 'rvhich have :no common iconfusable characteristic of form, and delineating on said support additional letters which have a form characteristic added thereto more clearly identifying said letters under degraded facsimile reception. g a

-2. The method :of prep'ar'mg a message c'opy composed of numeral characters for reduction optical copy scanning for signal pick-up for transmissionwhich comprises, printing on a suib able support numerals which hav'e'no com'mon coniusa'ble characteristic of form, and delineating on said support additional numerals which have a form characteristic added thereto .more clearly identifying said letters iunder degraded facsimile-reception. 7

of character confusion by -interfe'ren'ceinreception in an electrical (facsimile system employing 7 3. The method of preparing a message copy composed of alphabetic characters for reduction or character confusion by interference in reception in an electrical facsimile system employing optical copy scanning for signal pick-up for transmission in which said characters comprise seemingly vertical and horizontal strokes, characterized by. forming the B, the P, and the R, with horizon-tail strokes each at a different altitude position with respect to the height of said letters above their base line;

strokes that are employed in the delineating of r I 4. The method of preparing a message copy composed of alphabetic characters for reduction of character confusion by interference in reception in an electrical facsimile system employing optical copy scanning for signal pick-up for transmission in which said characters comprise seemingly vertical and horizontal strokes, characterized by, forming the E, and the F, with horizontal strokes at a difierent altitude position with respect to the height of said letters above their base line.

5. The method of preparing a message copy composed of alphabetic characters for reduction of character confusion by interference in IECBP-r tion in an electrical "facsimile system employing optical copy scanning for signal pick-up for transmission in which said characters comprise seemingly'vcrtical and horizontal strokes, characterized by, forming the A and the Kwith horizontal strokes at a different altitude position with respect to the :height of said letters above their base line.

6. The method of preparing a message copy composed of numeral characters for reduction of character confusion by interference in reception in an electrical facsimile system employing optical copy scanning for signal pick-up for trans-mission in which said characters comprise seemingly vertical and horizontal strokes, characterized by, forming the 2, the 3, and the *5 with horizontal strokes :each at difierent altitude position with respect to the height of said numerals above their base line.

'1. The method of preparing a message copy composed-of numeral characters for reduction of character confusion by interference in reception in an electrical facsimile system employing optical copy scanning fors-ignal-pick-up for transmission in which said characters comprise seemingly vertical and horizontal strokes, characterized by, forming the 6,, the 8, and the 9, with horizontal strokes each at adifferent altitud position with respect to the height of said numerals above their baseline. 7

V .ii/roN'rFoRD MORRISON.

REFERENCES crrED l The following references are of record in the fileof this patent: 1

STATES TATENTS Number I Name .Date 2,080,333 Pend'ergast, May 11, 1937 2,210,706 Carlisle Aug. .6, .1940

7 FOREIGN PATENT-s 7 r Number "Country Date 528,849 Great Britain Got. 22, 1940 OTHER REFERENCES 

